The present invention generally relates to apparatus and methods for completing subterranean wells and, in a preferred embodiment thereof, more particularly relates to the completion of a subterranean well using a pre-drilled casing section having plugged side wall apertures therein which may be opened downhole in conjunction with the process of communicating an adjacent subterranean formation with the interior of the casing section via its side wall apertures.
In a conventional completion process for a subterranean well, a well bore is extended through a subterranean formation, and a tubular casing structure is coaxially positioned within the wellbore to maintain the integrity of the wellbore, and facilitate subsequent placement of various downhole tools in the well. After placement of the casing within the well bore, the casing is laterally enveloped within a cement liner structure by forcing cement downwardly through the casing, outwardly through its lower end, and back up the well bore along the exterior surface of the casing. The resulting external cement liner on the casing serves to prevent undesirable vertical communication between various formations via the space between the exterior side surface of the casing and the side surface of the well bore.
Next, an explosive-based perforating gun structure is lowered into the cemented-in casing to a position vertically adjacent the formation to be perforated. Firing of the perforating gun detonates various shaped explosive charges thereon, with each of the detonated shaped charges sequentially penetrating an adjacent portion of the casing side wall, the adjacent cement lining, and a portion of the formation extending outwardly from the cement lining. This explosive penetration of the formation operatively communicates it with the interior of the now perforated casing so that production fluid from the formation may enter the casing for appropriate retrieval and transport to the surface in a well known manner.
This conventional use of a perforating gun carries with it the usual risks, inconveniences and unreliability associated with dealing with highly explosive materials. Moreover, when utilizing a perforating gun the operator must often contend with the deploying, dropping and recovering the perforation equipment.
As can readily be seen from the foregoing, a need exists for improved apparatus and associated methods for communicating the interior of a well casing with a surrounding subterranean formation. It is to this need that the present invention is directed.